Iran has deployed a new counter-drone weapon — a rifle-shaped jamming device that the regime says can electronically separate a remotely piloted aircraft from its command pilot and even reprogram it to turn on its owner.

The development could be significant for the future of drone warfare. Unmanned aerial vehicles are taking on larger roles in anti-U.S. planning by Iran and other belligerents. The U.S. military routinely launches spy drones over the Persian Gulf as well as over Iraq and Syria.

Iran has tested and deployed suicide drones that it says can be launched against U.S. ships, which are targets of harassment by the Islamic Revolutionary Guard Corps’ navy.

Gen. Joseph Votel, who heads U.S. Central Command and oversees Persian Gulf operations, said UAVs are among several weapons Iran deploys to try to menace shipping.

“The way they affect us is they provide Iran with a layered capability where they can use their fast boats, they can use cruise missiles, they can use radars, they can use UAVs to potentially dominate specific areas,” Gen. Votel told the Senate Armed Services Committee on Thursday.

In Iraq and Syria, the Islamic State has become more proficient in reconfiguring off-the-shelf drones to spy on and attack U.S.-backed coalition forces. The Islamic State, known as ISIL, ISIS and Daesh, has affixed small bombs and accurately dropped them onto people and vehicles in and around Mosul, Iraq, according to its propaganda videos.

In Iraq and Syria, the U.S. military is constantly flying Predator and Reaper UAVs to hunt and bomb Islamic State terrorists, vehicles and hideouts.

Iran is deeply involved in Iraq, where it is directing various Shiite militias by the thousands against the Islamic State with a wary eye on Americans who operate nearby as advisers to Iraqi regular forces.

Iran’s hand-held, drone-jamming tool could be turned against the U.S.

“The device, which resembles a rifle, is capable of locking onto a drone and jamming its communications,” says an analysis from the Army’s Foreign Military Studies Office at Fort Leavenworth, Kansas.

Citing Iranian information, the analysis states: “Once the device locks onto a drone, its operator is no longer in control. It is also reported that it has hacking capabilities, potentially rerouting a targeted drone. Additionally, its hacking abilities may allow the device user to safely land a drone.”

A U.S. military spokesman in Iraq said there have been no reports of Iran using counter-drone jammers there.

Robert Maginnis, a retired Army officer and Islamic terrorism analyst, said Iran has killed Americans before and will try to do it again.

“Iran’s friends, the Russians and Chinese, for mutually beneficial reasons share technologies that could potentially compromise our assets in the Persian Gulf,” Mr. Maginnis said. “Keep in mind Iran’s Islamic Revolutionary Guard Corps created the terrorist group Hezbollah that killed hundreds of U.S. Marines in a barracks outside of Beirut in October 1983. The Iranians would like to do the same against a U.S. warship in the Gulf.”

The IRGC already has American blood on its hands in Iraq. During the 2007-2009 troop surge, it trained Shiite militants in tactics and in making powerful improvised explosive devices that killed hundreds of U.S. personnel.

“Iranians still chant ‘Death to America’ at national rallies, and therefore we should expect their behavior to match their rhetoric,” Mr. Maginnis said.

Iran has kicked off its largest military buildup in recent memory.

The National Council of Resistance of Iran, the main opposition coalition to Tehran’s theocratic regime, released a book last week that it says documents the confiscation of wealth and property by the rolling mullahs and the IRGC.

The book, “Iran: The Rise of the Revolutionary Guards’ Financial Empire,” contains calculations that Iran spent $13 billion on arms in 2015 compared with $3 billion in 2008.

The council says Iran spent $25 billion in Syria alone and $1 billion on Hezbollah militants in Lebanon.

Analysts at the Army’s Foreign Military Studies Office say Tehran will soon reveal new main battle tank, the Karrar, instead of buying Russian tanks.

But Iran also wants to import high-tech items. The suspicion is that Tehran is focusing more brain power on reverse-engineering foreign components so it can produce them domestically.

“Its willingness to reverse-engineer foreign products might ultimately create reticence among Russian and Chinese military officials about the long-term wisdom of high-technology sales to Iran,” the Foreign Military Studies Office analysis said.

At sea, Iran is attempting to expand its reach outside the Gulf by building catamarans as platforms for helicopters and troops.

“As Iran’s area of operations has shifted from the Persian Gulf to areas further afield — the northern Indian Ocean, the Gulf of Aden, Red Sea, and perhaps even the Mediterranean — it has taken pains to bolster its logistical capabilities and reach,” wrote Middle East analyst Michael Rubin. “It is in this context that Iran’s new catamaran capability becomes important, if it works.”

Gen. Votel told the Senate Armed Services Committee that the U.S. faces a “range of malign activities perpetrated by Iran and its proxies operating in the region. It is my view that Iran poses the greatest long-term threat to stability for this part of the world.”

Asked by Sen. Deb Fischer, Nebraska Republican, if Iran’s behavior has “improved or has it worsened” since the 2015 nuclear agreement negotiated by the Obama administration, Gen. Votel said: “I would describe it as destabilizing to the region. It has not been helpful to anything that I can see going on across the region.”

Committee Chairman John McCain, Arizona Republican, summed up the Middle East picture: “The sad reality is America’s strategic position in the Middle East is weaker today than it was eight years ago and the positions of Vladimir Putin’s Russia and Iranian regime and its terrorist proxies have improved. This is not a military failure. Instead, it is a failure of strategy a failure of policy and, most of all, a failure of leadership.”