The U.S. is laying the groundwork to build a type of missile banned by a Cold War-era pact unless Russia abandons its own pursuit of the weapons, U.S. officials said.

The U.S. military’s preliminary research and development, previously undisclosed, is aimed at potentially reviving an arsenal of prohibited ground-based, intermediate-range missiles if Moscow continues violating the pact, the officials said.

American officials say they don't want to end the Cold War-era accord, known as the Intermediate-range Nuclear Forces Treaty, or the INF, but rather bring Russia back into compliance. Washington hopes to show Moscow the kinds of new American weapons Russia’s armed forces would face if they don’t stop violating the INF, U.S. officials say.

The U.S. told Russia of its research project in recent weeks, according to U.S. officials, but said was ready to abandon it if Russia returns to compliance, the officials said.

“The idea here is we need to send a message to the Russians that they will pay a military price for violation of this treaty,” one U.S. official said. “We are posturing ourselves to live in a post-INF world…if that is the world the Russians want.”

A Russian official said Thursday that the U.S., not Moscow, has been violating the treaty through its missile-defense installations in Europe. The U.S. denies that claim. The official added that Russian President Vladimir Putin has said a U.S. treaty withdrawal would bring an “immediate and reciprocal” Russian response.


In meetings in Brussels last week, U.S. Defense Secretary Jim Mattis told allies that Washington was trying to use new leverage to push Moscow into compliance. He said Washington had no plans to abandon the INF.

“Our effort is to bring Russia back into compliance,” Mr. Mattis said last week. “It is not to walk away from the treaty.”

Arms Control The Intermediate-Range Nuclear Force, or INF, Treaty was signed by U.S. President Ronald Reagan and his Soviet counterpart Mikhail Gorbachev in Washington on Dec. 8, 1987. Key facts about the treaty: Banned the use of intermediate and shorter range missiles with a range of 500 kilometers to 5,500 kilometers (about 300 to 3,400 miles).

By 1991, it eliminated more than 2,700 U.S. and Soviet missiles, including hundreds of American Pershing IIs and Soviet SS-20s.

The U.S. gave up 846 missile systems and the Soviets scrapped 1,846 systems.

The U.S. missiles were in countries including Germany, the U.K., Italy, Belgium and the Netherlands.

The Soviet missiles were in Belarus, Bulgaria, then-Czechoslovakia, Ukraine and Russia, among others.

Source: U.S. State Department, Federal of American Scientists, INF Treaty documents.

The U.S. would only be in violation of the treaty if it tests, produces or fields the new ground-based cruise missile under development. Researching and designing the weapon doesn’t constitute a violation.

Mr. Mattis is trying to balance Washington’s more muscular response with European fears that the U.S. would abandon an arms-control pact that leaders on the continent saw as a critical milestone in reducing Cold War tensions.


The INF push is part of a larger effort to craft a new Russia strategy by the State and Defense Departments, U.S. officials said. The administration is making a push for a Ukraine peacekeeping deal and is trying to strengthen arms control accords that have frayed amid U.S.-Russian tensions, say U.S. officials.

This summer, Congress instructed the Pentagon to begin research and development on an intermediate-range, road-mobile, ground-launched missile system in response to Russia’s violations of the treaty. The Pentagon started preliminary research for the missile given the likelihood that it soon would be required by law, U.S. officials said.

The House and Senate passed legislation authorizing research and development of a conventional “ground mobile” cruise missile, adding an extra potential challenge to Russian defenses if deployed. The White House is likely to approve it in the coming weeks, U.S. officials said.

The legislation also requires the administration to develop a new plan for additional sanctions on Russia related to its violations of the INF and authorizes the administration to “invoke legal countermeasures,” including possible suspension of the treaty.


For months, the U.S. has sought ways to secure Russian compliance with the INF. The U.S. summoned Moscow in late 2016 to a mandatory meeting under a special treaty commission to answer for the alleged Russian violations, to no avail.

In March, Air Force Gen. Paul Selva, the vice chairman of the Joint Chiefs of Staff, said the Russians had violated the treaty by deploying a land-based cruise missile. The missile’s range puts it at odds with the treaty, U.S. officials have said.

U.S. President Ronald Reagan, right, and Soviet President Mikhail Gorbachev signed the Intermediate-Range Nuclear Forces treaty in the White House in 1987. Photo: REUTERS

The INF Treaty, signed by the U.S. and the Soviet Union in 1987, entered into force the following year and banned the use and production of nuclear and conventionally-armed missiles that fly between 500 and 5,500 kilometers (311 miles and 3,418 miles). It doesn’t ban those fired by ships or aircraft.

Russian officials have denied they are in violation of the treaty and instead have accused the Pentagon of violating the pact by installing Aegis Ashore missile defense systems in Romania and Poland. U.S. officials have denied that accusation, saying that the Aegis systems launch only missiles outside the parameters of the treaty.


The legislation calls on the administration to determine whether Russia’s RS-26 is banned by the INF or will be regulated as an intercontinental ballistic missile. Moscow also has stoked concern with its SSC-8 cruise missile.

The INF Treaty remains critical for Europe’s security. The pact removed American-made Pershing II missiles from Europe, along with Soviet RDS-10 Pioneer, known to NATO as the SS-20.

The usually stoic NATO Secretary-General, Jens Stoltenberg, grew passionate this month while defending the INF Treaty’s importance.

“I’m part of a political generation in Europe which really grew up with the very intense debate related to the deployment of the SS-20s and the Pershing,” he said. “We also very much welcomed the INF Treaty which then eliminated all these weapons in Europe. So, I think that the INF Treaty is a cornerstone.”

Write to Julian E. Barnes at julian.barnes@wsj.com, Paul Sonne at paul.sonne@wsj.com and Brett Forrest at brett.forrest@wsj.com