Why can't Congress stop Donald Trump's attacks on allies?

Donald Trump's attempt to annex the Danish sovereign territory of Greenland - backed by threats of tariffs and a thinly veiled threat of military force - has dealt a double blow to Europeans. First, their American ally, not just their Russian enemy, is threatening the NATO region. Second, a mix of cheers and embarrassed silence from most Republicans in Congress.

The US Congress is unable to fully stop Donald Trump's aggressive behavior and foreign policy decisions against allies in 2026, mainly due to several legal and political limitations:Lack of effective legislation and veto power: Members of Congress have introduced bills such as the 'NATO Unity Protection Act', which prevents NATO members from occupying or militarily controlling their territory. However, President Trump has the power to veto any bill, and the two-thirds supermajority required in Congress to override that veto is currently almost impossible to achieve due to party divisions Economic warfare and the power to impose tariffs: Trump has threatened to impose new tariffs on eight allies, including Denmark, over the Greenland issue. The president can unilaterally impose tariffs by declaring a national emergency or using trade laws, which Congress has limited direct legal intervention to control.The Republican Party's political equation: While many top Republican leaders are uncomfortable with Trump's tough comments on Greenland or NATO, a large portion of them are afraid to engage in direct conflict with him given his immense popularity. They don't want to risk angering voters ahead of the 2026 midterm elections.The president's extensive powers in foreign policy: Historically, the US Constitution has given the president vast powers in foreign policy and military conduct. Congress's War Powers Act has not been successful in restraining any president in the past, and the current administration considers the law unconstitutional.As an alternative, 'shadow diplomacy': Many members of Congress, unable to stop Trump directly, are conducting 'back-channel' or secret talks with allies on their own initiative to minimize the damage caused by Trump's behavior and reassure allies.

In short, legal procrastination, the president's veto power, and a lack of party unity have rendered Congress ineffective against Trump's anti-ally stance.