WASHINGTON - Weapons shouldn’t be handled like toys. Yet that’s what U.S. President Donald Trump is doing by using steel import duties to punish Turkey over a detained U.S. pastor. While national security is a legitimate reason to restrict trade, doing so on a whim hurts America. Congress has a good reason, though maybe not the resolve, to take the toys away.

Trump tweeted on Friday that he was doubling tariffs for Turkish steel to 50 percent – the reason being that steel imports haven’t fallen enough under previous levies, so adjusting them is in the national security interest. It looks a lot like revenge: earlier, a deal to free American pastor Andrew Brunson, who has been detained in Turkey for almost two years on terrorism-related charges, fell apart.

In fact, Turkey is one of the few countries where U.S. tariffs were already pretty effective. It was the seventh-largest source of U.S. steel imports, but volume has dropped by nearly 60 percent this year compared to last year. Steel imports from China, which the United States blames for a global glut, have slightly increased over the same period.

The already-tumbling Turkish lira tumbled further on Friday, falling as much as 18 percent against the U.S. dollar. President Tayyip Erdogan called it an act of economic war. At various times, Trump has also been upset with North Korea, China and Iran. Impulsive use of tariffs, sanctions or other economic tools hasn’t yet started a physical war, but it’s no longer unthinkable that it might.

It’s time, therefore, for lawmakers to take back the trade powers they’ve delegated to the president. The U.S. Constitution gives Congress authority over foreign commerce. Senators Bob Corker and Pat Toomey are among the Republicans proposing bills that would require congressional approval for tariffs that are imposed for national-security reasons.

Even that’s not enough. Given Trump’s impetuous nature, such oversight should be extended to all import duties. In a perfect world, lawmakers would temporarily revoke Trump’s tariff authority altogether if he can’t handle it responsibly. That’s not realistic. Still, Congress has a chance to be more muscular in reasserting its powers, and ideally it would do that before the president sparks a crisis.

On Twitter https://twitter.com/GinaChon

CONTEXT NEWS

- Turkey’s central bank said on Aug. 13 that it would provide liquidity and cut reserve requirements for Turkish banks to stop the slide in its currency. The Turkish lira has lost more than 40 percent of its value against the U.S. dollar this year.

- The lira fell by as much as 18 percent on Aug. 10 after U.S. President Donald Trump doubled tariffs for steel and aluminum imports from Turkey. The two countries had failed to agree on a deal to free an American pastor charged with espionage in Turkey. The move raised the duties to 50 percent for Turkish steel and 20 percent for aluminum.

- "I have just authorized a doubling of Tariffs on Steel and Aluminum with respect to Turkey as their currency, the Turkish Lira, slides rapidly downward against our very strong Dollar!” Trump tweeted. “Aluminum will now be 20% and Steel 50%. Our relations with Turkey are not good at this time!"

- For previous columns by the author, Reuters customers can click on

- SIGN UP FOR BREAKINGVIEWS EMAIL ALERTS http://bit.ly/BVsubscribe

(Editing by John Foley and Martin Langfield)

© Reuters News 2018