A bipartisan group of national security professionals, including more than half a dozen former intelligence officials, sent an open letter calling on GOP presidential nominee Donald Trump Donald John TrumpBubba Wallace to be driver of Michael Jordan, Denny Hamlin NASCAR team Graham: GOP will confirm Trump's Supreme Court nominee before the election Southwest Airlines, unions call for six-month extension of government aid MORE to disclose his foreign business dealings.

"Donald Trump still has not revealed to the American public his international business relationships, even as it becomes increasingly clear that his overseas ties could well constitute significant conflicts of interest when it comes to charting US foreign policy," read the letter, published Monday.

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"This is unprecedented for a candidate for the nation's highest office. As such, we are calling on Mr. Trump to disclose, in full, the nature of his business relationships overseas — to include specifically who his business partners are and what and where are his foreign investments. We also call on him to pledge that he will divest himself of his overseas business interests should he win the presidency," it said.

The letter was spearheaded by Michael Morrell, former acting director and deputy director of the CIA; Michael Vickers, former undersecretary of Defense for intelligence; and former National Security Council senior staffer Sam Vinograd.

A number of former senior defense officials have also signed the letter, including Michele Flournoy, who is widely speculated to become Defense secretary if Democratic nominee Hillary Clinton Hillary Diane Rodham ClintonJoe Biden looks to expand election battleground into Trump country Biden leads Trump by 12 points among Catholic voters: poll The Hill's Campaign Report: Biden goes on offense MORE is elected.

The letter was signed predominantly by Democrats but includes a handful of Republicans as well.

Notable among the Republican signatories is Paul Wolfowitz, former deputy secretary of Defense under George W. Bush, who has not made an endorsement yet but has said, "I might have to vote for Hillary Clinton."

In a statement to The New York Times, the Trump campaign dismissed the letter, noting that one of the signatories is Wendy Sherman, the administration's lead negotiator on the Iran nuclear deal.

"If Wendy Sherman is the definition of who is considered a reliable government official, this letter and its signatories lose all credibility," Jason Miller, a Trump campaign spokesman, said.

"Based on her complete failure in representing American foreign policy and deep ties to Secretary Clinton, this letter epitomizes the rigged system in Washington that has continued to fail Americans over and over again," he said.

The letter cites a Sept. 15 article by Newsweek that said Trump courted former Libyan dictator Moammar Gadhafi. The report said Trump's other business partners have included "Kremlin-tied oligarchs and Russians with mafia links, an individual accused of money laundering for the Iranian military, a Turkish media tycoon accused of running a fuel-smuggling ring, Indian companies that may have violated India’s laws in their pursuit of business with Mr. Trump, and a South Korean company mired in scandal."

The article also said Trump's business partnerships owe millions of dollars to Chinese entities.

"It’s not hard to see why these reported relationships would be problematic. They could impact the foreign policy Mr. Trump would pursue as president, and they seem to have already influenced the policy positions he has taken as a candidate," the letter said.

The letter in particular cites Trump's business connections with Russia and his comments on the campaign trail praising Russian President Vladimir Putin.

"We do not know whether all of the facts in the Newsweek article are accurate, and the best way to dispel any doubts would be with a full and complete disclosure. The issues are too important to leave them unanswered. It would be in Trump’s own interest to resolve these potential conflicts before the election," the letter said.

The names on the letter include:

Gen. John R. Allen, USMC (Ret.), former Deputy Commander of the U.S. Central Command; former Commander, NATO International Security Assistance Force and U.S. Forces Afghanistan

Wendy Anderson, former Chief of Staff to the Deputy Secretary of Defense; former Chief of Staff to the Secretary of Commerce

Jeremy Bash, former Chief of Staff to the Director of the Central Intelligence Agency; former Chief of Staff to the Secretary of Defense

Rand Beers Rand BeersNational security figures urge Trump to disclose foreign business ties DNC creates cybersecurity board The Hill's 12:30 Report MORE, former Acting Secretary and Deputy Secretary of Homeland Security

Daniel Benjamin, former Ambassador-at-Large and Coordinator for Counterterrorism for the Department of State

Jarrod Bernstein, former Assistant Secretary of Intergovernmental Affairs for the Department of Homeland Security

Richard Betts, Director, Saltzman Institute of War and Peace Studies, Columbia University; Member, National Commission on Terrorism

Robert Blackwill, former Deputy Assistant to the President and Deputy National Security Advisor for Strategic Planning

David Buckley, former Inspector General, Central Intelligence Agency

Stan Byers, former Director for Afghanistan, National Security Council, the White House

Shamila N. Chaudhary, former Director for Afghanistan & Pakistan, National Security Council, the White House

Michael Chertoff, former Secretary of Homeland Security

Harry Clark, former Senior Counselor, U.S. Trade Representative

Jane Chapman Gates, former speechwriter for the Secretary of the Treasury; former Deputy Spokesman for U.S. Ambassadors to the UN; and former Senior Advisor to the President's Special Envoy to Sudan

Charles Dunne, former Foreign Policy Adviser to the Director for Strategic Plans and Policy at the Joint Staff in the Pentagon; former Director for Iraq, National Security Council, the White House

Evelyn Farkas, former Deputy Assistant Secretary of Defense for Russia/Ukraine/Eurasia

Gerald Feierstein, Ambassador (ret.)

Thomas Fingar, former Deputy Director of National Intelligence for Analysis; former Assistant Secretary of State for Intelligence and Research

Michele Flournoy, former Undersecretary of Defense for Policy

James K. Glassman, former Undersecretary of State for Public Diplomacy and Public Affairs; former Chairman, U.S. Broadcasting Board of Governors

Caitlin Hayden, former Spokesperson, National Security Council, the White House

Bruce Hoffman, former scholar-in-residence for counterterrorism, Central Intelligence Agency; former Commissioner, 9/11 Review Commission

Robert Kagan, Senior Fellow at the Brookings Institution and contributing columnist for the Washington Post

Stephen D. Krasner, Professor of Political Science, Stanford University; former Director of Policy Planning, Department of State

Mark P. Lagon, former Ambassador-At-Large to Combat Trafficking in Persons, Department of State

George Little, former Press Secretary for the Department of Defense; former Spokesman for the Central Intelligence Agency

John MacLaughlin, former Acting Director and Deputy Director of the Central Intelligence Agency

Anja Manuel, former Department of State official and Lecturer at Stanford University

James N. Miller, former Undersecretary of Defense for Policy

Michael Morell, former Acting Director and Deputy Director of the Central Intelligence Agency

Richard Nephew, former Principal Deputy Coordinator of Sanctions Policy for the Department of State

Thomas Nides, former Deputy Secretary of State

Maria Otero, former Undersecretary of State for Civilian Security, Democracy and Human Rights

Robert Pape, Professor of Political Science, University of Chicago

Mira Patel, former Small Business Administration Senior Advisor; former Policy Planning Staff, Department of State

Ricardo Reyes, former Deputy Assistant for Public and Media Affairs for the U.S. Trade Representative

John A. Rizzo, former Acting General Counsel for the Central Intelligence Agency

Andrew Sagor, former Special Assistant to the Ambassador-at-Large for War Crimes Issues, Office of the Secretary, Department of State

Dr. Gary Samore, former White House Coordinator for Arms Control and WMD Terrorism

Ronald P. Sanders, former Associate Director of National Intelligence

Kori Schake, former Deputy Director of Policy Planning, Department of State; former Director for Defense Strategy and Requirements, National Security Council, the White House

Stephen Sestanovich, former Ambassador-at-large for the former Soviet Union

Andrew J. Shapiro, former Assistant Secretary of State for Political Military Affairs

Nick Shapiro, former Deputy Chief of Staff for the Central Intelligence Agency; former Senior Advisor to the Deputy National Security Advisor; and former White House Assistant Press Secretary

Wendy Sherman, former Undersecretary of State for Political Affairs

Steven Simon, former Senior Director for the Middle East and North Africa, National Security Council, the White House

Julianne Smith, former Deputy National Security Advisor to Vice President Joseph Biden

Alan Steinberg, former Region 2 Environmental Protection Agency Administrator

John Stubbs, former Senior Advisor to the U.S. Trade Representative

Eric P. Schwartz, former Assistant Secretary of State for Population, Refugees, and Migration; former Senior Director, National Security Council, the White House

(Hon.) Ellen Tauscher, former Undersecretary of State for Arms Control and International Affairs

Michael Vickers, former Undersecretary of Defense for Intelligence

Samantha Vinograd, former Senior Advisor to National Security Advisor Thomas E. Donilon; former Director for International Affairs and for Iraq, National Security Council, the White House

Paul Wolfowitz, Chairman US-Taiwan Business Council; former Deputy Secretary of Defense; former U.S. Ambassador to Indonesia; and former Assistant Secretary of State for East Asia & the Pacific

Philip Zelikow, former Counselor of the Department of State; former Executive Director of the 9/11 Commission; and former member of the National Security Council staff, the White House