■ Iran began enriching uranium to higher levels and seized a tanker near the Strait of Hormuz.

DUBAI, United Arab Emirates — Iran began enriching uranium Monday to levels unseen since its 2015 nuclear deal with world powers and also seized a South Korean-flagged tanker near the crucial Strait of Hormuz, a double-barreled challenge to the West that further raised Mideast tensions.

Both decisions appeared aimed at increasing Tehran’s leverage in the waning days in office for President Donald Trump, whose unilateral withdrawal from the atomic accord in 2018 began a series of escalating incidents.

Increasing enrichment at its underground Fordo facility puts Tehran a technical step away from weapons-grade levels of 90 percent, while also pressuring President-elect Joe Biden to quickly negotiate. Iran’s seizure of the MT Hankuk Chemi comes as a South Korean diplomat was due to travel to the Islamic Republic to discuss the release of billions of dollars in Iranian assets now frozen in Seoul.

Iranian Foreign Minister Mohammad Javad Zarif seemed to acknowledge Tehran’s interest in leveraging the situation in a tweet about its nuclear enrichment.

“Our measures are fully reversible upon FULL compliance by ALL,” he wrote.

Iranian state television quoted government spokesman Ali Rabiei as saying that President Hassan Rouhani had given the order to begin the production. It came after its parliament passed a bill, later approved by a constitutional watchdog, aimed at increasing enrichment to pressure Europe into providing sanctions relief.

Iran’s decision to begin enriching to 20 percent purity a decade ago nearly triggered an Israeli strike targeting its nuclear facilities, tensions that only abated with the 2015 atomic deal, which saw Iran limit its enrichment in exchange for the lifting of economic sanctions.