Iran is in possession of improved and dangerous weapons systems that give Tehran the ability to threaten some of the world's most important waterways, according to the top American admiral in the Middle East.

Acting U.S. Defense Secretary Patrick Shanahan arrived in Baghdad on Tuesday for an unannounced visit during which he said he would stress the importance of Iraqi sovereignty and broach the issue of the future of U.S. troops there.

The Pentagon's top official made an unannounced visit to Afghanistan on Monday to meet with U.S. commanders and Afghan leaders amid a push for peace with the Taliban.

Russia would be prepared to consider new proposals from the United States to replace a suspended Cold War-era nuclear pact with a broader treaty that includes more countries, Deputy Foreign Minister Sergei Ryabkov said on Thursday.

President Trump warned China and Russia not to seek to win an arms race with the United States, and instead proposed negotiations to expand a recently scrapped nuclear arms control pact.

Secretary of State Mike Pompeo is expected to announce the U.S. intention to withdraw from the Intermediate-Range Nuclear Forces Treaty as soon as Friday, according to three U.S. officials familiar with the decision.

American and Taliban officials have agreed in principle to the framework of a peace deal in which the insurgents guarantee to prevent Afghan territory from being used by terrorists, and that could lead to a full pullout of American troops in return for a cease-fire and Taliban talks with the Afghan government, the chief United States negotiator said Monday.

Backed by Venezuela's military, President Nicolas Maduro went on the offensive against an opposition leader who declared himself interim president and his U.S. supporters, setting up a potentially explosive struggle for power in the crisis-plagued South American nation.