WASHINGTON - Canada's deputy prime minister says the country's relationship with the United States is getting "constant gardening" as the federal government works to keep supply lines open despite the COVID-19 crisis.

Chrystia Freeland says Canada finally received a vital shipment of N95 masks late Tuesday from 3M, a U.S.-based manufacturer that pushed back against government orders that it stop exporting the increasingly scarce equipment.

She says Canada's ties with the U.S. have always required constant upkeep, and that the two countries have been engaged in a constant effort to ensure vital trade lifelines that go in both directions remain unhindered.

Freeland says the U.S. needs Canada as much as Canada needs the U.S., a message diplomatic staff have been delivering for weeks now.

Earlier today, the Federal Emergency Management Agency issued draft rules for how the U.S. will be allocating domestic production of critical medical supplies, primarily masks and gloves.

Companies will be allowed to continue to fill existing standing orders for foreign clients, provided 80 per cent of their domestic production was allocated to the U.S. market over the previous 12 months.