China’s announcement of military drills around Taiwan as U.S. House Speaker Nancy Pelosi visits the island is already having ripple effects across global supply chains, prompting detours and causing delays of energy shipments.

Gas suppliers are rerouting or reducing speed on some liquefied natural gas vessels currently en route to North Asia, according to people familiar with the matter. Shipments to Taiwan and Japan this weekend will be affected, said the people, who requested anonymity as the information isn’t public.

Shipping companies are reassessing their options after China’s response to the visit of the highest-ranking U.S. official to the island in 25 years. The actions threaten to disrupt one of the world’s busiest waterways.